Methods for generating stem cell-derived beta cells and methods of use thereof

ABSTRACT

Disclosed herein are methods for generating SC-β cells, and isolated populations of SC-β cells for use in various applications, such as cell therapy.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 62/093,974 filed on Dec. 18, 2014, the entire teachings of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Diabetes affects more than 300 million people worldwide according to the International Diabetes Federation. Type 1 diabetes and type 2 diabetes involve 1 cell destruction and/or β cell dysfunction. Diabetic patients, particularly those suffering from type 1 diabetes, could potentially be cured through transplantation of β cells. While cadaveric human islet transplantation can render patients insulin independent for 5 years or longer, such approach is limited due to the scarcity and quality of donor islets (Bellin et al., 2012). Generating an unlimited supply of human β cells from stem cells could provide therapy to millions of patients as only a single cell type, the β cell, likely needs to be produced, and the mode of delivery is well understood: transplantation to a vascularized location within the body with immunoprotection. In addition, screening to identify novel drugs that improve β cell function, survival, or proliferation is also delayed due to limited islet supply and variability resulting from different causes of death, donor genetics, and other aspects in their isolation. As such, a steady, uniform supply of stem-cell-derived β cells would offer a useful drug discovery platform for diabetes. Moreover, genetically diverse stem-cell-derived β cells could be used for disease modeling in vitro or in vivo.

SUMMARY OF THE INVENTION

There is a need for methods of generating stem cell-derived β (SC-β) cells. The present invention is directed toward solutions to address this need, in addition to having other desirable characteristics.

In accordance with an embodiment of the present invention, a method for generating stem cell-derived β (SC-β) cells is provided. The method includes contacting a cell population with agents to direct differentiation to SC-β cells under conditions that promote cell clustering with additional agents comprising one or more of a) an effective amount of an agent that decreases the level and/or activity of rho-associated protein kinase (Rock) while the cell population comprises i) FOXA2+, SOX2+ primitive foregut cells differentiating to PDX1+ pancreatic progenitor cells, ii) PDX1+ pancreatic progenitor cells differentiating into PDX1+, NKX6.1+ pancreatic progenitor cells, and/or iii) PDX1+, NKX6.1+ pancreatic progenitor cells differentiating to chromogranin A, NKX6.1+ endocrine progenitor cells; b) an effective amount of Activin A while the cell population comprises PDX1+ pancreatic progenitor cells differentiating to PDX1+, NKX6.1+ pancreatic progenitor cells; and c) an effective amount of staurosporine while the cell population comprises PDX1−, NKX6.1+ pancreatic progenitor cells differentiating to chromogranin A, NKX6.1+ endocrine progenitor cells, thereby generating SC-β cells.

In accordance with aspects of the present invention, the method further comprises optionally washing the cell population after the PDX1+ pancreatic progenitor cells have differentiated to PDX1+, NKX6.1+ pancreatic progenitor cells to remove Activin A from contact with the cell population before contacting the cell population with staurosporine.

In accordance with aspects of the present invention, the agent comprises Y-27632. In accordance with aspects of the present invention, the effective amount of the agent comprises a concentration of 10 μM.

In accordance with aspects of the present invention, the effective amount of Activin A comprises a concentration of 5 ng/mi. In accordance with aspects of the present invention, the effective amount of staurosporine comprises a concentration of 3 nM.

In accordance with aspects of the present invention, the cell population comprising PDX1+ pancreatic progenitor differentiating to PDX1+, NKX6.1+ pancreatic progenitor cells is exposed to the agent and Activin A for a period of 6 days.

In accordance with aspects of the present invention, between at least between 75% and 80% of the cell population differentiates to chromogranin A, NKX6.1+ endocrine progenitor cells before differentiating to SC-β cells.

In accordance with aspects of the present invention, the agent i) prevents or minimizes cell cluster disintegration, ii) promotes cell survival, iii) increases cell cluster size, and combinations thereof.

In accordance with an embodiment of the present invention, an isolated SC-β cell or population thereof that exhibits a glucose stimulated insulin secretion (GSIS) response both in vitro and in vivo is provided. In accordance with aspects of the present invention, the isolated SC-β cell or population thereof exhibits a stimulation index that is at least between 1.0 and 3.0. In accordance with aspects of the present invention, the isolated SC-β cell or population thereof produces between approximately 300 uIU and 4000 uIU per 30 minute incubation at a high glucose concentration.

In accordance with an embodiment of the present invention, a microcapsule comprising the isolated SC-β cell or population thereof encapsulated therein is provided.

In accordance with an embodiment of the present invention, a macroencapsulation device comprising the isolated SC-β cell or population thereof encapsulated therein is provided.

In accordance with an embodiment of the present invention, a cell line comprising isolated SC-β cells that stably express insulin is provided.

In accordance with an embodiment of the present invention, assays comprising the isolated SC-β cell, or population thereof, or the cell line are provided. The assays can be used for: i) identifying one or more candidate agents which promote or inhibit a β cell fate selected from the group consisting of β cell proliferation, β cell replication, β cell death, β cell function, β cell susceptibility to immune attack, and β cell susceptibility to dedifferentiation or differentiation; or ii) identifying one or more candidate agents which promote the differentiation of at least one insulin-positive endocrine cell or a precursor thereof into at least one SC-β cell.

In accordance with an embodiment of the present invention, a method for the treatment of a subject in need thereof is disclosed. The method includes administering to a subject in need thereof i) an isolated population of SC-β cells, ii) a microcapsule comprising SC-β cells encapsulated therein; and/or iii) a macroencapsulation device comprising the SC-β cells encapsulated therein. In accordance with an embodiment of the present invention, an isolated population of SC-β cells, a microcapsule comprising the isolated population of SC-β cells, and/or a macroencapsulation device comprising the isolated population of SC-β cells is used for administering to a subject in need thereof. In accordance with aspects of the invention, the subject has, or has an increased risk of developing diabetes or has, or has an increased risk of developing a metabolic disorder.

In accordance with an embodiment of the present invention, an artificial islet or pancreas comprising SC-β cells is provided.

The practice of the present invention will typically employ, unless otherwise indicated, conventional techniques of cell biology, cell culture, molecular biology, transgenic biology, microbiology, recombinant nucleic acid (e.g., DNA) technology, immunology, and RNA interference (RNAi) which are within the skill of the art. Non-limiting descriptions of certain of these techniques are found in the following publications: Ausubel, F., et al., (eds.), Current Protocols in Molecular Biology, Current Protocols in Immunology, Current Protocols in Protein Science, and Current Protocols in Cell Biology, all John Wiley & Sons, N.Y., edition as of December 2008; Sambrook, Russell, and Sambrook, Molecular Cloning: A Laboratory Manual, 3rd ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, 2001; Harlow, E. and Lane, D., Antibodies—A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, 1988; Freshney, R. I., “Culture of Animal Cells, A Manual of Basic Technique”, 5th ed., John Wiley & Sons, Hoboken, N.J., 2005. Non-limiting information regarding therapeutic agents and human diseases is found in Goodman and Gilman's The Pharmacological Basis of Therapeutics, 11th Ed., McGraw Hill, 2005, Katzung, B. (ed.) Basic and Clinical Pharmacology, McGraw-Hill/Appleton & Lange; 10th ed. (2006) or 11th edition (July 2009). Non-limiting information regarding genes and genetic disorders is found in McKusick, V. A.: Mendelian Inheritance in Man. A Catalog of Human Genes and Genetic Disorders. Baltimore: Johns Hopkins University Press, 1998 (12th edition) or the more recent online database: Online Mendelian Inheritance in Man, OMIM™. McKusick-Institute of Genetic Medicine, Johns Hopkins University (Baltimore, Md.) and National Center for Biotechnology Information, National Library of Medicine (Bethesda, Md.), as of May 1, 2010, World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim/ and in Online Mendelian Inheritance in Animals (OMIA), a database of genes, inherited disorders and traits in animal species (other than human and mouse), at http://omia.angis.org.au/contact.shtml. All patents, patent applications, and other publications (e.g., scientific articles, books, websites, and databases) mentioned herein are incorporated by reference in their entirety. In case of a conflict between the specification and any of the incorporated references, the specification (including any amendments thereof, which may be based on an incorporated reference), shall control. Standard art-accepted meanings of terms are used herein unless indicated otherwise. Standard abbreviations for various terms are used herein.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will be more fully understood by reference to the following detailed description in conjunction with the attached drawings. The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawings will be provided by the Office upon request and payment of the necessary fee.

FIG. 1A and FIG. 1B are images of cells obtained using an exemplary control protocol for generating SC-β cells and cells obtained using a method for generating SC-β cells according to an embodiment of the present invention, respectively, demonstrating that the method for generating SC-β cells according to the present invention prevents or minimizes cell cluster disintegration, promotes cell survival, and increases cell cluster size and number.

FIG. 2A are FACS plots demonstrating that the cells obtained at each differentiation stage (S4, S5, and S6) using a method for generating SC-β cells according to an embodiment of the present invention maintain marker expression.

FIG. 2B are FACS plots of cells (e.g., SC-β cells) obtained using a control (e.g., DMSO) at the end of Step 6 (left panel) and cells (e.g., SC-β cells) obtained at the end of Step 6 of method for generating SC-β cells according to an embodiment of the present invention (right panel), demonstrating that staurosporine treatment generates a near pure endocrine population.

FIG. 2C are FACS plots of cells (e.g., SC-β cells) obtained using a control (e.g., DMSO) at the end of Step 6 (left panel) and cells (e.g., SC-β cells) obtained at the end of Step 6 of method for generating SC-β cells according to an embodiment of the present invention (right panel), demonstrating that staurosporine treatment generates a higher percentage of NKX6.1+, C-Peptide+ cells.

FIG. 3A is a schematic illustrating six stages of differentiation of human pluripotent stem cells to SC-β cells. hPSC=human pluripotent stem cell, DE=definitive endoderm cell, GT=gut tube cell, PP1=pancreatic progenitor cell 1, PP2=pancreatic progenitor cell 2, EN=endocrine progenitor cell, SC-β=stem cell-derived β cells.

FIG. 3B is a schematic illustrating an exemplary six step differentiation protocol for generating SC-β cells from pluripotent stem cells, as described further in Pagliuca et al. 2014 and PCT International Application No. PCT/US2014/041992.

FIG. 4A is a schematic illustrating an exemplary method for generating SC-β cells according to an embodiment of the present invention, e.g., by contacting a cell population directed to differentiate to SC-β cells under conditions that promote cell clustering with an agent that decreases the level and/or activity of rho-associated protein kinase (Rock inhibitor), a TGF-β superfamily member (e.g., Activin A), and a protein kinase inhibitor (e.g., staurosporine) during the steps indicated.

FIG. 4B is a schematic illustrating an exemplary method for generating SC-β cells according to an embodiment of the present invention, e.g., by contacting a cell population directed to differentiate to SC-β cells under conditions that promote cell clustering with an agent that decreases the level and/or activity of rho-associated protein kinase (Rock inhibitor), a TGF-β superfamily member (e.g., Activin A), and a protein kinase inhibitor (e.g., staurosporine) during the steps indicated, and in which Step 4 is carried out for an additional 24 hours compared to the method depicted in FIG. 4A.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to generating SC-β cells, in particular SC-β cells that exhibit in vitro and in vivo function. More particularly, work described herein demonstrates that contacting S2 cells, S3 cells, and S4 cells during Step 3, Step 4 and Step 5 with a Rock inhibitor with Activin A present during Step 4 in accordance with an embodiment of the present invention prevents or minimizes cell cluster disintegration, promotes cell survival, and increases the cell cluster size and number of cells in the resulting cell populations as compared to a control, as is shown in FIG. 1A (control) and FIG. 1B. Additionally, work described herein demonstrates that contacting S4 cells during Step 5 with staurosporine together with the Rock inhibitor and in the absence of Activin A generates cells that maintain marker expression as shown in FIG. 2A, as well as generates a near pure endocrine population as shown in FIG. 2B, and a higher percentage of NKX6.1+, C-Peptide+ cells as shown in FIG. 2C. The SC-β cells generated in accordance with the methods of the present invention can be used in various assays to identify novel drugs that improve β cell function, survival, or proliferation, cell therapies (e.g., for treating diabetes and/or metabolic disorders), and in the construction of artificial islets and/or an artificial pancreas.

Some Definitions

“Differentiation” is the process by which an unspecialized (“uncommitted”) or less specialized cell acquires the features of a specialized cell such as, for example, a pancreatic cell. A differentiated cell is one that has taken on a more specialized (“committed”) position within the lineage of a cell. The term “committed”, when applied to the process of differentiation, refers to a cell that has proceeded in the differentiation pathway to a point where, under normal circumstances, it will continue to differentiate into a specific cell type or subset of cell types, and cannot, under normal circumstances, differentiate into a different cell type or revert to a less differentiated cell type. As used herein, the lineage of a cell defines the heredity of the cell, i.e., which cells it came from and to what cells it can give rise. The lineage of a cell places the cell within a hereditary scheme of development and differentiation. A lineage-specific marker refers to a characteristic specifically associated with the phenotype of cells of a lineage of interest and can be used to assess the differentiation of an uncommitted cell to the lineage of interest.

As used herein, “markers”, are nucleic acid or polypeptide molecules that are differentially expressed in a cell of interest. Differential expression means an increased level for a positive marker and a decreased level for a negative marker as compared to an undifferentiated cell. The detectable level of the marker nucleic acid or polypeptide is sufficiently higher or lower in the cells of interest compared to other cells, such that the cell of interest can be identified and distinguished from other cells using any of a variety of methods known in the art.

As used herein, a cell is “positive” or “+” for a specific marker (e.g., expresses the marker) when the specific marker is sufficiently detected in the cell. Similarly, the cell is “negative” or “−” for a specific marker when the specific marker is not sufficiently detected in the cell. For example, positive by FACS is usually greater than 2%, whereas the negative threshold by FACS is usually less than 1%.

The process of differentiating pluripotent stem cells into functional pancreatic endocrine cells (i.e., SC-β cells) in vitro may be viewed in some aspects as progressing through six consecutive stages, as is shown in the exemplary protocol depicted in FIG. 3A. In this step-wise progression, “Stage 1” or “S1” refers to the first step in the differentiation process, the differentiation of pluripotent stem cells into cells expressing markers characteristic of definitive endoderm cells (“DE”, “Stage 1 cells” or “S1 cells”). “Stage 2” refers to the second step, the differentiation of cells expressing markers characteristic of definitive endoderm cells into cells expressing markers characteristic of gut tube cells (“GT”, “Stage 2 cells” or “S2 cells”). “Stage 3” refers to the third step, the differentiation of cells expressing markers characteristic of gut tube cells into cells expressing markers characteristic of pancreatic progenitor 1 cells (“PP1”, “Stage 3 cells” or “S3 cells”). “Stage 4” refers to the fourth step, the differentiation of cells expressing markers characteristic of pancreatic progenitor 1 cells into cells expressing markers characteristic of pancreatic progenitor 2 cells (“PP2”, “Stage 4 cells” or “S4 cells”). “Stage 5” refers to the fifth step, the differentiation of cells expressing markers characteristic of pancreatic progenitor 2 cells into cells expressing markers characteristic of pancreatic endoderm cells and/or pancreatic endocrine progenitor cells (“EN”, “Stage 5 cells” or “S5 cells”). “Stage 6” refers to the differentiation of cells expressing markers characteristic of pancreatic endocrine progenitor cells into cells expressing markers characteristic of pancreatic endocrine β cells (“SC-β cells”, “Stage 6 cells” or “S6 cells”). It should be appreciated, however, that not all cells in a particular population progress through these stages at the same rate, i.e., some cells may have progressed less, or more, down the differentiation pathway than the majority of cells present in the population.

Characteristics of the various cell types associated with the stages shown in FIG. 3A are now described. “Definitive endoderm cells,” as used herein, refers to cells which bear the characteristics of cells arising from the epiblast during gastrulation and which form the gastrointestinal tract and its derivatives. Definitive endoderm cells express at least one of the following markers: FOXA2 (also known as hepatocyte nuclear factor 3β (“HNF3β”)), GATA4, SOX17, CXCR4, Brachyury, Cerberus, OTX2, goosecoid, C-Kit, CD99, and MIXL1, Markers characteristic of the definitive endoderm cells include CXCR4, FOXA2 and SOX17. Thus, definitive endoderm cells may be characterized by their expression of CXCR4, FOXA2 and SOX17. In addition, depending on the length of time cells are allowed to remain in Stage 1, an increase in HNF4a may be observed.

“Gut tube cells,” as used herein, refers to cells derived from definitive endoderm that can give rise to all endodermal organs, such as lungs, liver, pancreas, stomach, and intestine. Gut tube cells may be characterized by their substantially increased expression of HNF4α over that expressed by definitive endoderm cells. For example, a ten to forty fold increase in mRNA expression of HNF4a may be observed during Stage 2.

“Pancreatic progenitor 1 cells,” as used herein, refers to endoderm cells that give rise to the esophagus, lungs, stomach, liver, pancreas, gall bladder, and a portion of the duodenum. Pancreatic progenitor 1 cells express at least one of the following markers: PDX1, FOXA2, CDX2, SOX2, and HNF4α. Pancreatic progenitor 1 cells may be characterized by an increase in expression of PDX1, compared to gut tube cells. For example, greater than fifty percent of the cells in Stage 3 cultures typically express PDX1.

“Pancreatic progenitor 2 cells,” as used herein, refers to cells that express at least one of the following markers: PDX1, NKX6.1, HNF6, NGN3, SOX9, PAX4, PAX6, ISL1, gastrin, FOXA2, PTF1a, PROX1 and HNF4α. Pancreatic progenitor 2 cells may be characterized as positive for the expression of PDX1, NKX6.1, and SOX9.

“Pancreatic endocrine progenitor cells” or “endocrine progenitor cells” are used interchangeably herein to refer to pancreatic endoderm cells capable of becoming a pancreatic hormone expressing cell. Pancreatic endocrine progenitor cells express at least one of the following markers; NGN3; NKX2.2; NeuroD1; ISL1; PAX4; PAX6; or ARX. Pancreatic endocrine progenitor cells may be characterized by their expression of NKX2.2 and NeuroD1.

A “precursor thereof” as the term relates to a pancreatic endocrine progenitor cell refers to any cell that is capable of differentiating into a pancreatic endocrine progenitor cell, including for example, a pluripotent stem cell, a definitive endoderm cell, a gut tube cell, or a pancreatic progenitor cell, when cultured under conditions suitable for differentiating the precursor cell into the pancreatic pro endocrine cell.

“Pancreatic endocrine cells,” as used herein, refer to cells capable of expressing at least one of the following hormones: insulin, glucagon, somatostatin, ghrelin, and pancreatic polypeptide. In addition to these hormones, markers characteristic of pancreatic endocrine cells include one or more of NGN3, NeuroD1, ISL1, PDX1, NKX6.1, PAX4, ARX, NKX2.2, and PAX6. Pancreatic endocrine cells expressing markers characteristic of β cells can be characterized by their expression of insulin and at least one of the following transcription factors: PDX1, NKX2.2, NKX6.1, NeuroD1, ISL1, HNF30, MAFA and PAX6.

The terms “stem cell-derived β cell” and “SC-β cell” are used interchangeably herein to refer to non-native cells differentiated in vitro (e.g., from pluripotent stem cells) that display at least one marker indicative of a pancreatic β cell (e.g., PDX-1 or NKX6-1), expresses insulin, and display a GSIS response characteristic of an endogenous mature β cell both in vitro and in vivo. The GSIS response of the SC-β cells can be observed within two weeks of transplantation of the SC-β cell into a host (e.g., a human or animal). It is to be understood that the SC-β cells need not be derived (e.g., directly) from stem cells, as the methods of the disclosure are capable of deriving SC-β cells from any endocrine progenitor cell that expresses insulin or precursor thereof using any cell as a starting point (e.g., one can use embryonic stem cells, induced-pluripotent stem cells, progenitor cells, partially reprogrammed somatic cells (e.g., a somatic cell which has been partially reprogrammed to an intermediate state between an induced pluripotent stem cell and the somatic cell from which it was derived), multipotent cells, totipotent cells, a transdifferentiated version of any of the foregoing cells, etc, as the invention is not intended to be limited in this manner). In some aspects, human cells are excluded that are derived from human embryonic stem cells obtained exclusively by a method necessitating the destruction of an embryo. The skilled artisan is well aware of such methods and how to avoid them for the purposes of generating SC-β cells according to the methods of the present invention.

Used interchangeably herein are “d1”, “1d”, and “day 1”; “d2”, “2d”, and “day 2”, etc. These number letter combinations refer to a specific day of incubation in the different stages during the stepwise differentiation protocol of the instant application.

Methods for Generating SC-β Cells

Recently, two protocols for directing the differentiation of pluripotent stem cells into insulin-producing endocrine cells that express key markers of mature pancreatic β cells (e.g., SC-β cells) have been reported, each of which includes differentiating cells into endocrine progenitor cells that can be directed to differentiate into SC-β cells as well as protocols for directing the pancreatic endocrine progenitor cells into SC-β cells, which can be used in the method disclosed herein for generating SC-β cells. First, as is shown in FIG. 3B, a six-stage protocol for the large-scale production of functional human β cells using human pluripotent stem cells (hPSC) by sequential modulation of multiple signaling pathways in a three-dimensional cell culture system, without using any transgenes or genetic modification, was used to generate glucose-responsive, monohormonal insulin-producing cells that exhibited key β cell markers and β cell ultrastructure (see Pagliuca et al., 2014 and PCT International Application No. PCT/US2014/041992, both of which are incorporated herein by reference in their entirety). Pagliuca and colleagues reported that such cells mimicked the function of human islets in vitro and in vivo, and demonstrated the potential utility of such cells for in vivo transplantation to treat diabetes. Secondly, a seven-stage protocol that converts human embryonic stem cells (hESCs) into insulin-producing cells that expressed key markers of mature pancreatic β cells, such as MAFA, and displayed glucose-stimulated insulin secretion like that of human islets using static incubations in vitro was described (Rezania et al., 2014). Cells produced by such protocol, referred to as S7 cells, were found to rapidly reverse diabetics in mice within a little over a month.

FIG. 4A shows an exemplary method for generating SC-β cells in accordance with an embodiment of the present invention that results in larger cell clusters comprising greater numbers of SC-β cells exhibiting a more pure endocrine population and greater number of SC-β cells exhibiting co-expression of NKX6.1 and C-peptide.

In accordance with an example embodiment of the present invention, a method for generating stem cell-derived β (SC-β) cells comprises contacting a cell population directed to differentiate to SC-β cells under conditions that promote cell clustering with a) an effective amount of an agent that decreases the level and/or activity of rho-associated protein kinase (Rock) while the cell population comprises i) FOXA2+, SOX2+ primitive foregut cells differentiating to PDX1+ pancreatic progenitor cells, ii) PDX1+ pancreatic progenitor cells differentiating into PDX1+, NKX6.1+ pancreatic progenitor cells, and/or iii) PDX1+, NKX6.1+ pancreatic progenitor cells differentiating to chromogranin A, NKX6.1+ endocrine progenitor cells; b) an effective amount of a TGF-β superfamily member while the cell population comprises ii) PDX1+ pancreatic progenitor cells differentiating to PDX1+, NKX6.1+ pancreatic progenitor cells; and c) an effective amount of a protein kinase inhibitor while the cell population comprises iii) PDX1+, NKX6.1+ pancreatic progenitor cells differentiating to chromogranin A, NKX6.1+ endocrine progenitor cells, thereby generating SC-β cells.

“Contacting”, “contacting the cell” and any derivations thereof as used herein, refers to any means of introducing an agent (e.g., nucleic acids, peptides, ribozymes, antibodies, small molecules, etc.) into a target cell or an environment in which the cell is present (e.g., cell culture), including chemical and physical means, whether directly or indirectly. Contacting also is intended to encompass methods of exposing a cell, delivering to a cell, or ‘loading’ a cell with an agent by viral or non-viral vectors, and wherein such agent is bioactive upon delivery. The method of delivery will be chosen for the particular agent and use. Parameters that affect delivery, as is known in the medical art, can include, inter alia, the cell type affected, and cellular location. In some aspects, contacting includes administering the agent to a subject. In some aspects, contacting refers to exposing a cell or an environment in which the cell is located (e.g., cell culture medium) to at least one agent that decreases the level and/or activity of Rock (also referred to herein as “ROCK inhibitor”). In some aspects, contacting refers to exposing a cell or an environment in which the cell is located (e.g., cell culture medium) to a TGF-β superfamily member (e.g., Activin A). In some aspects, contacting refers to exposing a cell or an environment in which the cell is located (e.g., cell culture medium) to a protein kinase inhibitor (e.g., staurosporine).

In accordance with aspects of the present invention, the method includes an optional step of washing the cell population after the PDX1+ pancreatic progenitor cells have differentiated to PDX1+, NKX6.1+ pancreatic progenitor cells to remove Activin A from contact with the cell population before contacting the cell population with staurosporine.

The methods of the present invention contemplate: i) contacting cells or cell populations (e.g., comprising S2, S3, and S4 cells) with an effective amount of one or more Rock inhibitors; ii) contacting cells or cell populations (e.g., comprising S3 cells) with an effective amount of a TGF-β superfamily member (e.g., Activin A); and iii) contacting cells or cell populations (e.g., comprising S4 cells) with an effective amount of a protein kinase inhibitor (e.g., staurosporine). An “effective amount” of an agent (or composition containing such agent) refers to the amount sufficient to achieve a desired effect, e.g., when delivered to a cell or subject according to a selected administration form, route, and/or schedule. As will be appreciated by those of ordinary skill in this art, the absolute amount of a particular agent or composition that is effective may vary depending on such factors as the desired biological or pharmacological endpoint, the agent to be delivered, the target tissue, etc. Those of ordinary skill in the art will further understand that an “effective amount” may be contacted with cells or administered in a single dose, or the desired effect may be achieved by use of multiple doses. An effective amount of a composition may be an amount sufficient to reduce the severity of or prevent one or more symptoms or signs of a disorder (e.g., diabetes). In some aspects, the effective amount of the agent that decreases the level and/or activity of ROCK comprises a concentration of between about 0.1 μM and about 110 μM. In some aspects, the effective amount of the agent (e.g., ROCK inhibitor) comprises 10 μM. In some aspects, the effective amount of the TGF-μ superfamily member comprises a concentration of between about 1 ng/ml to about 1000 ng/ml. In some aspects, the effective amount of the TGF-β superfamily member comprises 5 ng/ml. In some aspects, the effective amount of the protein kinase inhibitor comprises a concentration of between about 0.1 nM and 110 nM. In some aspects, the effective amount of the protein kinase inhibitor comprises a concentration of 3 nM.

The present invention contemplates using any agent that decreases the level and/or activity of ROCK in the methods for generating SC-β cells, e.g., ROCK inhibitors can be small organic or inorganic molecules; saccharides; oligosaccharides; polysaccharides; biological macromolecules, e.g., peptides, proteins, and peptide analogs and derivatives; peptidomimetics; nucleic acids and nucleic acid analogs and derivatives (including but not limited to microRNAs, siRNAs, shRNAs, antisense RNAs, a ribozymes, and aptamers); an extract made from biological materials such as bacteria, plants, fungi, or animal cells; animal tissues; naturally occurring or synthetic compositions; and any combinations thereof.

Exemplary ROCK inhibitors include, but are not limited to a small organic molecule ROCK inhibitor selected from the group consisting of N-[(1S)-2-Hydroxy-1-phenylethyl]-N′-[4-(4-pyridinyl)phenyl]-urea (AS1892802), fasudil hydrochloride (also known as HA 1077), -[3-[[2-(4-Amino-1,2,5-oxadiazol-3-yl)-1-ethyl-1H-imidazo[4,5-c]pyridin-6-yl]oxy]phenyl]-4-[2-(4-morpholinyl)ethoxy]benzamide (GSK269962), 4-[4-(Trifluoromethyl)phenyl]-N-(6-Fluoro-1H-indazol-5-yl)-2-methyl-6-oxo-1,4,5,6-tetrahydro-3-pyridinecarboxamide (GSK 429286), (5)-(+)-2-Methyl-1-[(4-methyl-5-isoquinolinyl)sulfonyl]-hexahydro-1H-1,4-diazepine dihydrochloride (H 1152 dihydrochloride), (S)-(+)-4-Glycyl-2-methyl-1-[(4-methyl-5-isoquinolinyl)sulfonyl]-hexahydro-1H-1,4-diazepine dihydrochloride (glycyl-H 1152 dihydrochloride), N-[(3-Hydroxyphenyl)methyl]-N′-[4-(4-pyridinyl)-2-thiazolyl]urea dihydrochloride (RKI 1447 dihydrochloride), (3S)-1-[[2-(4-Amino-1,2,5-oxadiazol-3-yl)-1-ethyl-1H-imidazo[4,5-c]pyridin-7-yl]carbonyl]-3-pyrrolidinamine dihydrochloride (SB772077B dihydrochloride), N-[2-[2-(Dimethylamino)ethoxy]-4-(1H-pyrazol-4-yl)phenyl-2,3-dihydro-1,4-benzodioxin-2-carboxamide dihydrochloride (SR 3677 dihydrochloride), and trans-4-[(1R)-1-Aminoethyl]-N-4-pyridinylcyclohexanecarboxamide dihydrochloride (Y-27632 dihydrochloride), N-Benzyl[2-(pyrimidin-4-yl)amino]thiazole-4-carboxamide (Thiazovivin), Rock Inhibitor, a isoquinolinesulfonamide compound (Rho Kinase Inhibitor), N-(4-Pyridyl)-N′-(2,4,6-trichlorophenyl)urea (Rho Kinase Inhibitor II), 3-(4-Pyridyl)-1H-indole (Rho Kinase Inhibitor III, Rockout), and 4-pyrazoleboronic acid pinacol ester; a Rock antibody commercially available from Santa Cruz Biotechnology selected from the group consisting of Rock-1 (B1), Rock-1 (C-19), Rock-1 (H-11), Rock-1 (G-6), Rock-1 (H-85), Rock-1 (K-18), Rock-2 (C-20), Rock-2 (D-2), Rock-2 (D-11), Rock-2 (N-19), Rock-2 (H-85), Rock-2 (30-J); a ROCK CRISPR/Cas9 knockout plasmid selected from the group consisting of Rock-1 CRISPR/Cas9 KO plasmid (h), Rock-2 CRISPR/Cas9 KO plasmid (h), Rock-1 CRISPR/Cas9 KO plasmid (m), Rock-2 CRISPR/Cas9 KO plasmid (m); a ROCK siRNA, shRNA plasmid and/or shRNA lentiviral particle gene silencer selected from the group consisting of Rock-1 siRNA (h): sc-29473, Rock-1 siRNA (m): sc-36432, Rock-1 siRNA (r): sc-72179, Rock-2 siRNA (h): sc-29474, Rock-2 siRNA (m): sc-36433, Rock-2 siRNA (r): se-108088.

In some aspects, a ROCK inhibitor decreases the level and/or activity of ROCK in cells contacted by at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 95% relative to the level or activity of ROCK in the cells in the absence of contact with the ROCK inhibitor. While not required, a ROCK inhibitor can completely inhibit the level and/or activity of ROCK in the cells. It should be appreciated that the ROCK inhibitors may decrease the level and/or activity of ROCK in any cell in the population in which the S2, S3 and/or S4 cells are differentiating, including endocrine progenitor cells in population, SC-β cells, and any precursors thereof.

In accordance with aspects of the present invention, the agent (e.g., ROCK inhibitor) comprises Y-27632.

An effective amount of Y-27632 for use in the methods of the present invention can be, for example, between about 0.1 μM and about 110 μM. In some aspects, an effective amount of tY-27632 comprises 10 μM.

The present invention contemplates using any agent TGF-β superfamily member. Exemplary such members include, but are not limited to, Nodal, Activin A, Activin B, bone morphogenic protein-2 (BMP2), bone morphogenic protein-4 (BMP4) and functional fragments thereof. In accordance with aspects of the present invention, the TGF-β superfamily member comprises Activin A.

An effective amount of Activin A for use in the methods of the present invention can be, for example, between about 1 ng/ml to about 1000 ng/ml. In accordance with aspects of the present invention, an effective amount of Activin A comprises a concentration of 5 ng/ml.

The present invention contemplates using any protein kinase inhibitor that is capable of generating a near pure endocrine population or increasing the number of cells in the population coexpressing and NKX6.1+, C-peptide in the methods for generating SC-β cells.

In accordance with aspects of the present invention, the protein kinase inhibitor comprises staurosporine. An effective amount of staurosporine for use in the methods of the present invention can be, for example, between about 0.1 nM and about 110 nM. In accordance with aspects of the present invention, an effective amount of staurosporine comprises a concentration of 3 nM.

In accordance with aspects of the present invention, as is shown in FIG. 4B, the cell population comprising ii) PDX1+ pancreatic progenitor differentiating to PDX1+, NKX6.1+ pancreatic progenitor cells is exposed to the agent and TGF-β superfamily member (e.g., Activin A) for a period of 6 days.

Preferably, a maximum number of cells in the population differentiate to chromogranin A, NKX6.1+ endocrine progenitor cells before differentiating into SC-β cells. The number of cells in the population differentiating to chromogranin A, NKX6.1+ endocrine progenitor cells before differentiating into SC-β cells is 5%, 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or more. In accordance with aspects of the present invention, between at least between 75% and 80% of the cell population differentiates to chromogranin A, NKX6.1+ endocrine progenitor cells before differentiating to SC-β cells.

SC-β Cells Obtained by the Method of Generating SC-β Cells

In accordance with an embodiment of the present invention, an isolated SC-β cell or population thereof generated according to a method described herein is provided. The isolated SC-β cell or population exhibits a GSIS response both in vitro and in vivo. The isolated SC-β cell or population also exhibits at least one characteristic feature of a mature endogenous β cell (e.g., monohormonality). In some aspects, an isolated SC-β cell or population thereof exhibits a stimulation index of between about 1.0 and about 3.0. In some aspects, an isolated SC-β cell or population thereof produces between approximately 300 uIU to about 4000 uIU per 30 minute per 10⁶ total cells incubation at a high glucose concentration.

The SC-β cells disclosed herein share many distinguishing features of native β cells, but are different in certain aspects (e.g., gene expression profiles). In some embodiments, the SC-β cell is non-native. As used herein, “non-native” means that the SC-β cells are markedly different in certain aspects from β cells which exist in nature, i.e., native β cells. It should be appreciated, however, that these marked differences typically pertain to structural features which may result in the SC-β cells exhibiting certain functional differences, e.g., although the gene expression patterns of SC-β cells differs from native β cells, the SC-β cells behave in a similar manner to native β cells but certain functions may be altered (e.g., improved) compared to native β cells. For example, a higher frequency of SC-β cells respond to 20 mM glucose compared to the frequency of native β cells. Other differences between SC-β cells and native β cells would be apparent to the skilled artisan based on the data disclosed herein.

The SC-β cells of the disclosure share many characteristic features of β cells which are important for normal β cell function. For example, the SC-β cells (e.g., human) generated according to the methods described herein may further exhibit at least one of the following characteristics of an endogenous mature pancreatic β cell: i) a response to multiple glucose challenges that resembles the response of endogenous islets (e.g., at least one, at least two, or at least three or more sequential glucose challenges); ii) a morphology that resembles the morphology of an endogenous β cell; iii) packaging of insulin into secretory granules or encapsulated crystalline insulin granules; iv) a stimulation index of greater than at least 1.4; v) cytokine-induced apoptosis in response to cytokines; vi) enhanced insulin secretion in response to known antidiabetic drugs (e.g., secretagogues); vii) monohormonal, i.e., they do not abnormally co-express other hormones, such as glucagon, somatostatin or pancreatic polypeptide; viii) a low rate of replication; and ix) increased intracellular Ca²⁺ in response to glucose.

In accordance with an embodiment of the present invention, a microcapsule comprising the isolated SC-β cell or population thereof encapsulated therein is provided.

In accordance with an embodiment of the present invention, a macroencapsulation device comprising the isolated SC-β cell or population thereof is provided.

In accordance with an embodiment of the present invention, a cell line comprising an isolated SC-β cell that stably expresses insulin is provided.

Assays

In accordance with an embodiment of the present invention, an isolated SC-β cell or population thereof generated according to the methods herein, or an SC-β cell that stably expresses insulin, can be used in various assays. In some aspects, an isolated SC-β cell, population thereof, or an SC-β cell that stably expresses insulin, can be used in an assay to identify one or more candidate agents which promote or inhibit a β cell fate selected from the group consisting of β cell proliferation, β cell replication, β cell death, β cell function, β cell susceptibility to immune attack, and β cell susceptibility to dedifferentiation or differentiation. In some aspects, an isolated SC-β cell, population thereof, or an SC-β cell that stably expresses insulin, can be used in an assay to identify one or more candidate agents which promote the differentiation of at least one insulin-positive endocrine cell or a precursor thereof into at least one SC-β cell. The assays typically involve contacting the isolated SC-β cell, population thereof, or an SC-β cell that stably expresses insulin, with one or more candidate agents to be assessed for its ability to i) promote or inhibit a β cell fate selected from the group consisting of β cell proliferation, β cell replication, β cell death, β cell function, β cell susceptibility to immune attack, and β cell susceptibility to dedifferentiation or differentiation, or ii) promoting the differentiation of at least one insulin-positive endocrine cell or a precursor thereof into at least one SC-β cell and assessing whether the candidate agent possesses the ability to i) promote or inhibit a β cell fate selected from the group consisting of β cell proliferation, β cell replication, β cell death, β cell function, β cell susceptibility to immune attack, and β cell susceptibility to dedifferentiation or differentiation, or ii) promoting the differentiation of at least one insulin-positive endocrine cell or a precursor thereof into at least one SC-β cell.

Methods for Treatment

In accordance with an embodiment of the present invention, methods for the treatment of a subject in need thereof are provided. The methods entail administering to a subject in need thereof an isolated population of SC-β cells or a microcapsule comprising SC-β cells encapsulated therein. In some aspects, the subject is in need of additional β cells. In some aspects, the subject has, or has an increased risk of developing diabetes, A SC-β cell or population (e.g., isolated) of SC-β cells generated by a method of the present invention can be administered to a subject for treatment of type 1 or type 2 diabetes. In some aspects, the subject has, or has an increased risk of developing, a metabolic disorder. In some aspects, administering to the subject comprises implanting SC-β cells, a microcapsule comprising SC-β cells, or a macroencapsulation device comprising SC-β cells into the subject. The subject may be a human subject or an animal subject. In some aspects, the cells may be implanted as dispersed cells or formed into clusters that may be infused into the hepatic portal vein. In some aspects, cells may be provided in biocompatible degradable polymeric supports, porous non-degradable devices or encapsulated to protect from host immune response. Cells may be implanted into an appropriate site in a recipient. The implantation sites include, for example, the liver, natural pancreas, renal subcapsular space, omentum, peritoneum, subserosal space, intestine, stomach, or a subcutaneous pocket.

To enhance further differentiation, survival or activity of the implanted cells in vivo, additional factors, such as growth factors, antioxidants or anti-inflammatory agents, can be administered before, simultaneously with, or after the administration of the cells. These factors can be secreted by endogenous cells and exposed to the administered cells in situ. Implanted cells can be induced to differentiate by any combination of endogenous and exogenously administered growth factors known in the art.

The amount of cells used in implantation depends on a number of various factors including the patient's condition and response to the therapy, and can be determined by one skilled in the art.

In some aspects, the method of treatment further comprises incorporating the cells into a three-dimensional support prior to implantation. The cells can be maintained in vitro on this support prior to implantation into the patient. Alternatively, the support containing the cells can be directly implanted in the patient without additional in vitro culturing. The support can optionally be incorporated with at least one pharmaceutical agent that facilitates the survival and function of the transplanted cells.

Artificial Islet or Pancreas

In accordance with an embodiment of the present invention, an artificial islet or pancreas is provided. The artificial islet or pancreas can be constructed using the SC-β cells generated according to the methods described herein.

An artificial pancreas is a device that encapsulates and nurtures islets of Langerhans to replace the islets and β cells destroyed by type 1 diabetes. An artificial pancreas may contain a million islets or more, and may be implanted in the peritoneal cavity or under the skin where it can respond to changing blood glucose levels by releasing hormones, such as insulin. An artificial pancreas may be made using living (e.g., glucose-sensing and insulin secreting islets) and nonliving components (e.g., to shield the islets from the diabetic's body and its destructive immune mechanism while permitting the islets to thrive).

The present invention contemplates using β cells in any artificial pancreas. In some aspects, the artificial pancreas comprises microencapsulated or coated islets comprising SC-β cells generated according to the methods herein. In some aspects, the artificial pancreas comprises a macroencapsulation device into which islet cells comprising SC-β cells generated according to the methods herein are grouped together and encapsulated. In some aspects, the macroencapsulation device comprises a PVA hydrogel sheet for an artificial pancreas of the present invention (Qi et al., 2004). In some aspects, the artificial islet comprises SC-β cells generated according to the methods herein, along with other islet cells (α, δ, etc.) in the form of an islet sheet. The islet sheet comprises a layer of artificial human islets comprising the SC-β cells macroencapsulated within a membrane (e.g., of ultra-pure alginate). The sheet membrane is reinforced with mesh and may be coated on the surface to prevent or minimize contact between the cells encapsulated inside and the transplantation recipient's host immune response. Oxygen, glucose, and other nutrients readily diffuse into the sheet through the membrane nurturing the islets, and hormones, such as insulin readily diffuse out. Additional examples of membranes designed for macroencapsulation/implantation of an artificial islet or pancreas can be found in the literature (Isayeva et al. 2003). Another example of a macroencapsulated implant suitable for an artificial islet or pancreas can be found in the literature (Aurélien, et al. 2014).

Terminology

The articles “a”, “an” and “the” as used herein, unless clearly indicated to the contrary, should be understood to include the plural referents. Claims or descriptions that include “or” between one or more members of a group are considered satisfied if one, more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process unless indicated to the contrary or otherwise evident from the context. It should it be understood that, in general, where the invention, or aspects of the invention, is/are referred to as comprising particular elements, features, etc., certain embodiments of the invention or aspects of the invention consist, or consist essentially of, such elements, features, etc. For purposes of simplicity those embodiments have not in every case been specifically set forth in haec verba herein. It should also be understood that any embodiment of the invention, e.g., any embodiment found within the prior art, can be explicitly excluded from the claims, regardless of whether the specific exclusion is recited in the specification. For example, any agent may be excluded from the genera of ROCK inhibitors, TGF-β superfamily members, and protein kinase inhibitors.

Where ranges are given herein, the invention includes embodiments in which the endpoints are included, embodiments in which both endpoints are excluded, and embodiments in which one endpoint is included and the other is excluded. It should be assumed that both endpoints are included unless indicated otherwise. Furthermore, it is to be understood that unless otherwise indicated or otherwise evident from the context and understanding of one of skill in the art, values that are expressed as ranges can assume any specific value or subrange within the stated ranges in different embodiments of the invention, to the tenth of the unit of the lower limit of the range, unless the context clearly dictates otherwise. It is also understood that where a series of numerical values is stated herein, the invention includes embodiments that relate analogously to any intervening value or range defined by any two values in the series, and that the lowest value may be taken as a minimum and the greatest value may be taken as a maximum. Numerical values, as used herein, include values expressed as percentages. For any embodiment of the invention in which a numerical value is prefaced by “about” or “approximately”, the invention includes an embodiment in which the exact value is recited. For any embodiment of the invention in which a numerical value is not prefaced by “about” or “approximately”, the invention includes an embodiment in which the value is prefaced by “about” or “approximately”. “Approximately” or “about” generally includes numbers that fall within a range of 1% or in some embodiments 5% of a number in either direction (greater than or less than the number) unless otherwise stated or otherwise evident from the context (except where such number would impermissibly exceed 100% of a possible value).

Furthermore, it is to be understood that the invention encompasses all variations, combinations, and permutations in which one or more limitations, elements, clauses, descriptive terms, etc., from one or more of the listed claims is introduced into another claim dependent on the same base claim (or, as relevant, any other claim) unless otherwise indicated or unless it would be evident to one of ordinary skill in the art that a contradiction or inconsistency would arise. Where elements are presented as lists, e.g., in Markush group or similar format, it is to be understood that each subgroup of the elements is also disclosed, and any element(s) can be removed from the group.

Certain claims are presented in dependent form for the sake of convenience, but any dependent claim may be rewritten in independent format to include the limitations of the independent claim and any other claim(s) on which such claim depends, and such rewritten claim is to be considered equivalent in all respects to the dependent claim (either amended or unamended) prior to being rewritten in independent format. It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one act, the order of the acts of the method is not necessarily limited to the order in which the acts of the method are recited, but the invention includes embodiments in which the order is so limited. It is contemplated that all aspects described above are applicable to all different embodiments of the invention. It is also contemplated that any of the above embodiments can be freely combined with one or more other such embodiments whenever appropriate.

REFERENCES

-   1. Bellin et al., (2012). Potent induction immunotherapy promotes     long-term insulin independence after islet transplantation in type 1     diabetes. Am. J. Transplant. 12, 1576-1583. -   2. Pagliuca et al. (2014). Generation of Functional Human Pancreatic     β cells In Vitro. Cell. 159, 428-439. -   3. Rezania et al. (2014). Reversal of diabetes with     insulin-producing cells derived in vitro from human pluripotent stem     cells. Nat. Biotech. 32(11), 1121-1133. -   4. Isayeva, et al. (2003). Characterization and performance of     membranes designed for macroencapsulation/implantation of pancreatic     islet cells. Biomaterials 24(20), 3483-3491. -   5. Motté, et al. (2014). Composition and function of     macroencapsulated human embryonic stem cell-derived implants:     comparison with clinical human islet cell grafts. American Journal     of Physiology-Endocrinology and Metabolism 307(9), E838-E846. -   6. Qi et al. (2004). PVA hydrogel sheet macroencapsulation of the     bioartificial pancreas. Biomaterials 24(27), 5885-5892 

What is claimed is:
 1. A method comprising contacting a cell population comprising PDX1+ pancreatic progenitor cells that do not express NKX6.1 with a culture medium comprising rho-associated protein kinase (Rock) inhibitor and Activin A, wherein the contacting results in one or more cells in the cell population differentiating to PDX1+ pancreatic progenitor cells that express NKX6.1.
 2. The method of claim 1, further comprising washing the cell population after the PDX1+ pancreatic progenitor cells that do not express NKX6.1 have differentiated to PDX1+ pancreatic progenitor cells that express NKX6.1, wherein said washing is effective to remove Activin A from contact with the cell population.
 3. The method of claim 1, wherein the Rock inhibitor comprises Y-27632.
 4. The method of claim 1, wherein the culture medium comprises 10 μM of the Rock inhibitor.
 5. The method of claim 1, wherein the culture medium comprises 5 ng/ml of Activin A.
 6. The method of claim 1, wherein the cell population comprising PDX1+ pancreatic progenitor cells that do not express NKX6.1 is exposed to the Rock inhibitor and Activin A for a period of 6 days.
 7. The method of claim 1, wherein the method further i) prevents or minimizes cell cluster disintegration, ii) promotes cell survival, iii) increases number of PDX1+ pancreatic progenitor cells that express NKX6.1 in resulting cell population, and combinations thereof.
 8. A method comprising contacting a cell population comprising PDX1+, NKX6.1+ pancreatic progenitor cells with a culture medium comprising rho-associated protein kinase (Rock) inhibitor and staurosporine, wherein the contacting results in one or more cells in the cell population differentiating to chromogranin A, NKX6.1+ endocrine progenitor cells.
 9. The method of claim 8, further comprising differentiating the chromogranin A, NKX6.1+ endocrine progenitor cells to SC-β cells, wherein the SC-β cells exhibit co-expression of NKX6.1 and C-peptide.
 10. The method of claim 8, wherein the culture medium comprises 3 nM of staurosporine.
 11. The method of claim 8, wherein between at least 75% and 80% of the cell population differentiates to chromogranin A, NKX6.1+ endocrine progenitor cells before differentiating to SC-β cells. 